1. Field of the Invention
The invention relates to a process for making substantially solvent free quaternary ammonium compounds using fatty acids, amines and quaternizing agents without side reactions such as those reactions that would produce esters of fatty acids. A more fluid product is obtained than the ester-containing softener blends used for dryer softener sheets. Ordinarily quaternization of the amine takes place in the presence of the fatty acid and the quaternizing agent, resulting in the formation of the ester of the fatty acid which makes the resultant product viscous and difficult to handle. By employing the method of the present invention, in which a relatively small amount of a water-alcohol solvent is used in the quaternizing reaction after which a fatty acid is added and the solvent removed, a product is obtained which is ready to be flaked or powdered and can be used as a fabric softener, lubricant, hair conditioner, in the manufacture of aqueous dispersions and the like.
2. Brief Description of the Prior Art
The preparation of quaternary ammonium compounds is usually conducted in stainless steel or glass-lined equipment to which a tertiary amine is charged and a solvent. Flammable solvents such as isopropyl alcohol are generally used although mixtures of isopropyl alcohol and water sometimes are employed or water alone is used. Flammable solvents are undesirable because they are a fire hazard and special handling procedures are required when they are used. In many applications, these solvents have to be stripped from the mixture when the reaction is completed because the ultimate use of the product is in a solventless or solid form.
After the reactants are loaded into the reactor they are heated to a temperature of about 50.degree. to about 100.degree. C. after which a quaternizing reagent is added. In some instances an exotherm is produced as a result of the quaternizing reaction and the reactor and its contents have to be cooled. The rate of addition of the quaternizing agent can also be controlled in order to minimize or eliminate the exotherm. As noted previously, in some instances, the solvent, if any is employed in the quaternizing reaction is stripped from the quaternary ammonium compound obtained since some commercial uses for the compounds are in solventless systems. Additionally, bulk shipments of quaternary ammonium compounds with solvents adds to transportion costs which is another reason to remove the solvents.
It is also known in the prior art that when water alone is used as the solvent a gelatinous sticky mass is obtained from which the water is difficult to remove. When alcohol is used as the solvent for the quaternizing reaction the products obtained are not as difficult to handle as when water is used, however, when used, it presents not only a fire hazard but also an environmental problem if released to the air. The combinations of water and alcohol have been used for several years in quaternization reactions and this solvent mixture generally is removed by either sparging and/or by applying a vacuum to the quaternary ammonium compound thus produced which contains the solvents. These processes, although commercially employed are not entirely satisfactory primarily because the mixture of solvents with the quaternary ammonium compound and other reactants and by-products is viscous to the point where solvent removal can be difficult.
The largest use for quaternary ammonium compounds is as a fabric softener and presently accounts for more than about three quarters of the total market for these material. Some fabric softeners are supplied as a liquid dispersion of from about 3% to about 10% by weight of the quaternary ammonium compound which is adapted to be added during the rinse cycle of a commercial or home laundering operation. Another significant fabric softening application is the utilization of quaternary ammonium compounds in combination with a substrate such as a nonwoven fabric or a polymeric foam such as a polyurethane foam, this substrate so treated being added to a fabric dryer such as a clothes dryer while the fabric or clothes are still damp. The quaternary ammonium compound is formulated usually with a fatty acid or ester which promotes the transfer of the quaternary ammonium compound from the nonwoven or porous polymeric substrate to the fabric or clothes.
Quaternary ammonium compounds are now being added to both solid and liquid laundry detergent compositions so that the quaternary ammonium compound can be incorporated as a fabric softener during the wash cycle of fabrics or clothes. The most successfully utilized quaternary ammonium compounds in this last respect are the dimethyl (dihydrogenated tallow) ammonium chlorides or methyl sulfates. Other quaternary ammonium compounds such as imidazolines and amidoamine quaternaries are also used.
Quaternary ammonium compounds are also used to manufacture organomodified clays which may be added to drilling muds utilized in drilling oil wells, the organomodified clay providing improved lubrication and rheological properties of the drilling muds. These organoclays are also employed as thixotropic agents in plastisols, organosols, paints and other protective coatings, grease additives, foundry additives, cosmetics, resins and printing inks. The most common quaternary ammonium compounds employed in this regard are methyldi(hydrogenated tallow) benzylammonium chloride, dimethyldi(hydrogenated tallow) ammonium chloride and dimethyl(hydrogenated tallow) benzylammonium chloride.
Quaternary ammonium compounds are also employed as disinfectants, e.g. bactericides or bacteristats, the most common of which is the quaternary ammonium compound of benzylchloride and a dimethylalkyl-amine, the alkyl group having from about 12 to about 16 carbon atoms as well as trimethyl alkyl ammonium chlorides where the alkyl group is a long chain alkyl such as an octadecyl group. Additionally, dimethyldicoconut-oil fatty ammonium chlorides are also effective bactericides especially against anaerobic bacteria which are sulfate reducers that are found in oil wells, these bacteria causing severe corrosion problems and plugging of formations which this type of quaternary ammonium compound can minimize or eliminate. Additionally, these quaternary ammonium compounds effective against anaerobic bacteria are also effective in removing oil from sand stone formations in oil wells and provide a two-fold effect of functioning not only as a bactericide but also in promoting so-called secondary recovery of oil.
An additional use of quaternary compounds is in hair treatment because of the antistatic effects obtained with such compounds, as well as the increased wetting which promotes improvements in both wet and dry combing or brushing and improves luster and feel. The most commonly used quaternary ammonium compounds in this respect are trimethylalkylammonium chloride, pentaethoxystearylammonium chloride, dimethylstearylbenzylammonium chloride and dimethyldialkylammonium chlorides.
It is therefore an object to overcome these and other difficulties encountered in the prior art.
It is also an object of the present invention to provide a method for manufacturing a mixture of quaternary ammonium compounds with a fatty acid inter allia which can be used in fabric softening applications. It is also an object of the present invention to provide such mixtures.
It is a further object of the present invention to provide a method for making a mixture of a quaternary ammonium compound from which the solvents such as mixtures of water and alcohol can be readily removed by conventional methods such as sparging and/or vacuum.
It is also an object of the present invention to provide such a mixture which is relatively fluid so that the removal of solvents such as mixtures of alcohols and water is readily achieved by sparging and/or vacuum.
It is also an object of the invention to provide such mixtures with low amounts of solvents but are nonetheless relatively fluid so that the solvents such as water and alcohol can be readily removed by sparging and/or vacuum.
It is also an object of the invention to provide a method for making such mixtures for use as fabric softeners.
It is a further object of the present invention to provide a composition comprising such mixtures with low amounts of solvents such as water and alcohol that lend themselves to the easy removal of such solvents by sparging and/or vacuum.
It is a further object of the invention to provide mixtures of quaternary ammonium compounds with a fatty acid that can be employed in any or all of the foregoing applications.
These and other objects have been achieved according to the present invention which will be further understood in view of the following description and claims.